Patent Literature 1 discloses a vehicle displaying device that reflects the light of an LED on a front window glass to transmit the information to a driver. Patent Literature 2 discloses a vehicle drive supporting system that notifies a driver of danger by irradiating light of a light source installed in the vehicle to a position on a front glass surface corresponding to the detected position of danger at the exterior of the vehicle as the light reflecting on the background of the front glass.
Other conventional art literatures include patent Literatures 3 to 5. Patent Literature 3 discloses a vehicle head-up displaying device that irradiates the light of the LED on the front window through a diffusion plate. Patent Literature 4 discloses a vehicle displaying device that lowers the alarm level of an alarm when a driver confirms the alarm displayed on the window shield. Patent Literature 5 discloses a vehicle information presenting device that switches the display of the information to lower visual inducing property when the driver confirms the displayed information.